Plasma levels and pharmacokinetics of antipileptic drugs in children.
The Michaelis-Menten pharmacokinetics and bioavailability of phenytoin were evaluated in children. The Vmax was inversely related to age, but there was no such relationship for Km. The fraction excreted in urine as 5-(p-hydroxyphenyl)-5-phenylhydantoin, the main metabolite of phenytoin after oral administration, was not significantly different among the patients aged two months to 16 years; suggesting that no functional difference existed between children and adults would alter the drug absorption from the gastrointestinal tract. Children on sodium valproate mono-therapy were divided into three different age groups. The daily dose per kilogram of the body weight correlated poorly with the plasma concentration in each age group. However, the plasma level to dose ratio increased with the advancement of the group age. Also in children treated only with carbamazepine at daily doses of 10-15 mg/kg body weight, the younger age group achieved the lower steady-state plasma concentrations of carbamazepine. In contrast, the concentration of carbamazepine-10, 11-epoxide, the main metabolite of carbamazepine, expressed as a percentage of the parent drug, was higher in the younger age group.
D000293:Adolescent; D000367:Age Factors; D000927:Anticonvulsants / Q000097:blood*; D001682:Biological Availability; D001711:Biotransformation; D002220:Carbamazepine / Q000097:blood; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004827:Epilepsy / Q000097:blood*; D006801:Humans; D007700:Kinetics; D008657:Metabolic Clearance Rate; D010672:Phenytoin / Q000097:blood; D014635:Valproic Acid / Q000097:blood
D000927:Anticonvulsants; D002220:Carbamazepine; D014635:Valproic Acid; D010672:Phenytoin